Process for preparing carboranes



United States Patent 3,483,258 PROCESS FOR PREPARING CARBORANES Marvin M. Fein, Westfield, and John E. Paustian, Whippany, NJ and Bernard M. Lichstein, New York, N.Y., assignors, by direct and mesne assignments, of one-half each to Thiokol Chemical Corporation, Bristol, Pa., a corporation of Delaware and Olin Mathieson Corporation, New Haven, Conn., a corporation of Virginia No Drawing. Filed May 29, 1961, Ser. No. 113,547 Int. Cl. C07f /02 US. Cl. 260-6065 3 Claims ABSTRACT OF THE DISCLOSURE This invention relates to a method of preparation of organoboron compounds. This process involves the reaction between decarborane or alkylated decarboranes having 1 to 4 alkyl groups containing 1 to 5 carbon atoms in each group and acetylenic hydrocarbons containing from 2 to carbon atoms in the presence of amides or cyanamides. The products resulting from this process are useful as fuels.

Application Ser. No. 59,460 filed Sept. 29, 1960 of Jack Bobinski, Marvin M. Fein and Nathan Mayes discloses and claims a new class of organoboron compounds defined as (RC=)(R'C=)B ,,H ,,R" wherein R and R are hydrogen, alkyl radicals or alkenyl radicals, the total number of carbon atoms in R and R being from 0 to 8, R" is a lower alkyl radical, and n varies from 0 to 4. The organoboron compounds are prepared by the reaction of a bis(nitrilo)decaborane or a bis(nitrilo) alkyldecaborane with an acetylenic hydrocarbon containing from two to ten carbon atoms in the presence of an inert organic solvent. For example, C-isopropenylvinylenedccaborane of the formula can be prepared by heating isopropenyl acetylene with bis(acetonitrilo)decaborane in benzene at 50 C. for 24 hours. The organoboron compounds can be either solid or liquid and are useful as fuels.

In accordance with this invention, it was discovered that decaborane or alkylated decaboranes having 1 to 4 alkyl groups containing 1 to 5 carbon atoms in each group will react with an acetylenic hydrocarbon containing from two to ten carbon atoms in the presence of any of a wide variety of nitriles, amines, amides, cyanamides, or sulfides. Suitable nitriles include hydrogen nitriles of the saturated and unsaturated aliphatic mono and dicarboxylic acids containing 2 to 5 carbon atoms, hydrogen cyanide, acetonitrile, propionitrile, butyronitrile, isobutyronitrile, dimethyl propionitrile, valeronitrile, acrylonitrile, S-butenenitrile, 4-pentenenitrile, succinonitrile, malononitrile, adiponitrile and B,B-oxydipropionitrile. Suitable amines include lower alkyl amines, lower dialkyl amines, alkyl diamines containing 2 to 8 carbon atoms, methylamine, n-propylamine, ethylamine, isopropylamine, 2- aminopentane tert-amylamine, dimethylamine, diethylamine, di-n-propylamine, di-sec-butylamine, ethylenediamine, propylenediamine, 1,3-diaminobutane hexamethylenediamine, octamethylenediamine, N,N-dimethylaniline and o-chloroaniline. I

Suitable amides include amines of the saturated and unsaturated aliphatic monocarboxylic acids containing 1 to 5 carbon atoms, for example, formamide, acetamide, acrylamide, N,N-dimethylacetamide, N,N-dimethylformamide, N-ethylacetamide, propioamide, butyramide, valeramide, and isovaleramide. Suitable cyanamides include, for example, lower alkyl cyanamides, lower dialkyl cy- ICC anamides, cyanamide, methyl cyanamide, ethylcyanamide, n-propyl cyanamide, isopropylcyanamide, n-butyl-cyanamide, n-amyl-cyanamide, dimethylcyanamide, diethylcyanamide, di-n-propylcyanamide, di-n-butylcyanamide, methylethylcyanamide, n-amylethylcyanamide, and the like. Suitable sulfides include the lower dialkyl sulfides, dimethyl sulfide, diethyl sulfide, ethyl methyl sulfide, diisopropyl sulfide, ethyl propyl sulfide, butylmethyl sulfide, di-n-butyl sulfide and diphenyl sulfide.

The ratio of reactants can be varied widely, generally being in the range of 0.5 to 2.0 moles of decaborane or alkyldecaborane per mole of acetylenic compound and preferably in the range of 0.8 to 1.6 moles of decaborane or alkyldecaborane per mole of acetylenic compound. The ratio of nitrile, amine, amide, cyanamide, or sulfide to borane also can be varied widely, generally being in the range of 2 to 6 moles of nitrile, amine, amide, cyanamide, or sulfide per mole of decaborane or alkyldecaborane, and preferably being in the range of 3 to 4 moles of nitrile, amine, amide, cyanamide or sulfide per mole of decaborane or alkyldecaborane. The reaction temperature can vary widely, generally from 20 C. to 150 C. and preferably between 60 C. and 90 C. The reaction pressure can vary from subatmospheric to several atmospheres, i.e., from 0.5 to atmospheres, although atmospheric pressure reactions are convenient. The degree of completeness of the reaction can be determined by the rate and quantity of hydrogen evolved, the rate at which solid products form and precipitate from solution, or by analysis of the reaction mixture. The reaction generally requires about 1 to 12 hours, depending upon the ratio of reactants, the particular reactants and solvents employed and the temperature and pressure of the reaction.

The reaction can or need not be conducted in a solvent common for the reactants but inert with respect to the reactants. Such solvents include aliphatic hydrocarbon solvents such as n-pentane, hexane, and heptane, aromatic hydrocarbon solvents such as benzene, toluene and xylene, and cycloaliphatic solvents such as cyclohexane and methylcyclohexane. The amount of solvent can vary widely but generally ranges up to about 5 times the weight of the reactants.

' The process of the invention is illustrated in detail by the following examples.

EXAMPLE I A 250 ml. 3-neck flask was equipped with a magnetic stirror, a thermometer and a reflux condenser leading to a wet-test meter, Acetonitrile, 41.1 g. (1.0' mole), isopropenylacetylene, 14.5 g. (0.22 mole), benzene, ml., and decaborane, 24.5 g. (0.2 mole), were placed in the flask and the mixture stirred and heated to reflux. Refluxing was continued for 24 hours, during which time the reflux temperature rose from 62 to 71 C., the solution turned from yellow to orange to red-brown and 7.69 l. of gas (0.34 mole% of theory) was evolved. The reaction mixture was allowed to cool, the solids (9.17 g.) removed by filtration, and the filtrate stripped of solvent at 50 C. under reduced pressure. The residue was triturated with petroleum ether and a sticky mass was precipitated. The supernatant liquid was decanted, the solid re-extracted, and the supernatant phases were combined, filtered and evaporated to dryness to give 18.5 g. of a yellow waxy solid (50.5% yield) M.P. 4045. The identity of the material was greater than C-isopropenylvinylenedecaborane was made by infrared anaylsis.

EXAMPLE II A 500 ml. flask, equipped as above, was charged with 24.5 g. (0.2 mole) of decaborane, 60 ml. of benzene,

13.2 g. (0.2 mole) of isopropenylacetylene and 87.1 g. (1.0 mole) of N,N-dimethylacetamide. Gas evolution began at room temperature. The temperature was raised to 55 C. over a two hour period, during which time the mixture turned red and a copious precipitate was formed. The temperature was maintained at 55-60 C. for 22 hours, 8.2 l. of gas (82.5% of theory based on B H charged) was evolved, most of the precipitate dissolved, and the solution was yellow. The mixture was cooled and filtered to remove 12.3 g., of a yellow, gummy solid. The filtrate was extracted with four 100 ml. portions of water and the benzene layer was then stripped Of solvent. The residue was extracted several times with petroleum ether and the extracts were stripped of solvent. The crude residue was refluxed in methanol for three hours to destroy any non-vinylenedecaborane boron hydrides. Th: solvent was stripped to leave a light yellow solid, 15.1 g. (0.081 mole-40.6% yield), whose infrared spectrum confirmed the product as C-isopropenylvinylenedecarbane of reasonably high purity.

By a similar procedure, and with the same mole ratios, a 45.5% yield of C-isopropenylvinylenedecaborane was obtained when N,N-dirnethylformarnide Was used rather than N,N-dimethylacetamide.

EXAMPLE III A mixture of 6.1 g. (0.05 mole) decaborane, 50 ml. of benzene, 6.0 g. of isopropenylacetylene (0.09 mole) and 26 g. (0.25 mole) of butylmethyl sulfide was heated at reflux with agitation for 22 hours. At the end of this time 2.01. of gas (90% of theoretical based on B H charged) was evolved and the solution had turned yellow. The mixture was stripped of solvent under reduced pressure and 10.5 g. of an oil remained. The infrared spectrum of the oil revealed an absorption pattern consistent with that for .vl C-isopropenylvinylenedecaborane contaminated with boric acid and an aliphatic-CH component. Assay of the oil for C-isopropenylvinylenedecaborane content by measuring absorption at 1630 ml. on a Beckman Ratio Recording Spectrophotomaster, Model DK-2, revealed it contained 51%, product equivalent to 5.35 g., 58% yield.

We claim:

1. A method for the production of an organoboron compound useful as a fuel which comprises reacting with the formation of hydrogen a borane selected from the group consisting of decaborane and alkyl decaboranes having from one to four alkyl groups containing from one to five carbon atoms in each alkyl group and an acetylenic hydrocarbon containing from two to ten carbon atoms while the reactants are in admixture with a material selected from the group consisting of amides of saturated and unsaturated aliphatic monocarboxylic acids containing 1 to 5 carbon atoms, cyanamide, lower alkyl cyanamides and lower dialkyl cyanamides.

2. The method of claim 1 wherein said material in N,N- dimethylacctamide.

3. The method of claim 1 wherein said borane is decaborane, said acetylenic hydrocarbon is isopropenylacetylene, and said material is N,N-dirnethylacetamide.

No references cited.

TOBIAS E. LEVOW, Primary Examiner W. F. W. BELLAMY, Assistant Examiner U.S. Cl. X.R. 14922 

